WO2014013172A1

WO2014013172A1 - Device for forming mineral fibres

Info

Publication number: WO2014013172A1
Application number: PCT/FR2013/051687
Authority: WO
Inventors: Mohamed CHAKROUN
Original assignee: Saint-Gobain Isover
Priority date: 2012-07-16
Filing date: 2013-07-15
Publication date: 2014-01-23
Also published as: US20150191389A1; EP4079695A1; FR2993265B1; PL2872455T3; US20190055154A1; SI2872455T1; US10138156B2; US11117827B2; DK2872455T3; EP2872455B1; FR2993265A1; US20210355019A1; EP2872455A1; ES2920873T3

Abstract

The invention relates to a device for forming mineral fibres, comprising: a centrifuge (1) adapted to turn about an axis of rotation (9), the centrifuge (1) comprising an annular wall (10) drilled with a plurality of orifices (11), the annular wall (10) having for axis of symmetry the axis of rotation (9); a first annular inductor (2) adapted to heat the upper part of the annular wall (10); and a second annular inductor (5) adapted to heat the lower part of the annual (10). Thus, the invention allows efficiency to be increased and emission of carbon dioxide to be very greatly decreased or even prevented.

Description

DEVICE FOR FORMING MINERAL FIBERS

The invention relates to a device for forming mineral fibers by an internal centrifugation process. It applies in particular to the industrial production of glass wool intended to enter, for example, into the composition of thermal and / or acoustic insulation products.

Various internal centrifugation methods are known. A fillet of molten glass is introduced into a spinning plate rotating at high speed and pierced at its periphery by a very large number of orifices through which the glass is projected in the form of filaments under the effect of centrifugal force. These filaments can then be subjected to the action of an annular drawing stream at high temperature and speed along the wall of the centrifuge, stream which thins them and transforms them into fibers. The fibers formed are entrained by this draw gas stream to a receiving device generally consisting of a gas-permeable reception and conveyor belt.

This process has been the subject of many improvements, including for some on the fibering plate, for others on the means for generating the annular drawing current, for example by means of burners of particular type. See especially EP-B-0 189 354, EP-B-0 519 797, WO-A-97/15532 concerning this last point.

The document FR-A-1 382 917 describes a fiberizing device whose principle is still used extensively: the melt is brought into a basket having on its vertical wall orifices through which the material is projected onto the wall of a fibering plate which is integral with the basket and which comprises a large number of orifices. This wall is called a "band" of the fibering plate. In order to obtain quality fiber drawing, the orifices are distributed over annular rows and the diameters of the orifices are variable according to the row to which they belong, this diameter decreasing from the top of the strip to its lower part.

Improvements have been made to this basic principle, as taught in particular in document FR-A-2 443 436, in which means make it possible to obtain a laminar flow of the melt from the top to the bottom of the strip of the plate. Another modification, described in EP-A-1370496, has been made to improve the quality of the fibers and to increase the yield. This is to distribute the orifices of the strip into a plurality of annular zones arranged one above the other, with at least two annular zones having a number of orifices per unit area which is different from a higher value. or equal to 5%.

WO 03/069226 discloses an internal combustion burner comprising a combustion chamber in which at least one fuel supply and oxidizer feed conduit and at least one flame stabilizing element creating a containment zone in which at least one at least some of the combustion takes place.

In all of these examples, the peripheral strip of the plate is heated both by the molten glass which is centrifuged in the fiberizing plate and by the hot air blown by an internal combustion burner generating the ring current stretching.

However, heating by an internal combustion burner is a significant source of energy consumption, with an energy efficiency of less than 30%, and a very high source of carbon dioxide emissions.

There is therefore a need for a mineral fiber forming device that has decreased energy consumption and carbon dioxide content.

For this, the invention provides a device for forming mineral fibers comprising:

a centrifuge adapted to rotate about an axis of rotation, the centrifuge comprising an annular wall pierced with a plurality of orifices, the annular wall having as an axis of symmetry the axis of rotation,

a first annular inductor adapted to heat the upper part of the annular wall,

a second annular inductor adapted to heat the lower part of the annular wall.

According to another feature, the mineral fiber forming device further comprises a first blower ring adapted to blow air on the mineral fibers intended to exit the plurality of orifices of the annular wall. to convey them to a conveyor belt for receiving and conveying the fibers.

According to another feature, the mineral fiber forming device further comprises a second blower ring adapted to blow air on an area of the centrifuge located above the annular wall so as to control the temperature of the upper part. centrifuge.

According to another feature, the cooperation of the two blowing rings creates a zone of turbulence close to the annular wall of the centrifuge, this turbulence zone allowing additional stretching of the mineral fibers intended to exit the plurality of orifices of the annular wall. .

According to another feature, the device further comprises at least two concentric first concentric blow rings of different diameters, the cooperation of the first blow crowns creating a zone of turbulence near the annular wall of the centrifuge, this zone of turbulence permitting further stretching the mineral fibers to exit the plurality of orifices of the annular wall.

According to another feature, the first annular ring comprises a plurality of concentric air outlets creating a zone of turbulence near the annular wall of the centrifuge, this turbulence zone allowing additional stretching of the mineral fibers intended to exit the plurality of orifices. of the annular wall.

According to another feature, the second annular inductor, for example located under the centrifuge, is connected in series or in parallel with the first annular inductor. The first and second inductors are then preferably powered independently of one another.

According to another feature, the mineral fiber forming device further comprises an internal burner adapted to be used at startup of the mineral fiber forming device.

In another feature, the centrifuge comprises a bottom.

In another feature, the centrifuge does not include bottom and includes a basket. According to another feature, the mineral fiber forming device further comprises a crown of sizing mineral fibers located under the centrifuge.

The invention also relates to a process for the formation of mineral fibers by internal centrifugation, using the device described above, in which the fiber material is poured into the centrifuge.

Other features and advantages of the invention will now be described with reference to the drawings in which:

• Figure 1 shows a sectional view of a mineral fiber forming device according to the invention.

The "up", the "down", the "top" and the "bottom" are defined with respect to a vertical axis when the centrifuge is in the centrifugation position, that is to say when the rotation axis of the centrifuge is in the centrifugation position. centrifuge is along a vertical axis, as in Figure 1.

The invention relates to a device for forming mineral fibers. The device comprises a centrifuge adapted to rotate about an axis of rotation. The centrifuge comprises an annular wall, of axis of symmetry the axis of rotation, which is pierced with a plurality of orifices. The device also includes first and second annular inductors. The first annular inductor is adapted to heat the upper part of the annular wall of the centrifuge. The second annular inductor is adapted to heat the lower part of the annular wall of the centrifuge.

Thus, the heating of the centrifuge is achieved by electric induction, which increases the energy efficiency and greatly reduce or even cancel (if no internal burner is used), the carbon dioxide level, because No internal combustion annular burner producing hot gas flow is used.

Figure 1 shows a sectional view of a mineral fiber forming device according to the invention.

The mineral fiber device comprises a centrifuge 1, also called fiberizing plate, having an annular wall 10 pierced with a plurality of orifices 1 January. The centrifuge 1 also comprises a web 13. The web 13 forms the top of the centrifuge 1, between the annular wall and the tulip. The provision The formation of mineral fibers also comprises a shaft 15 of axis 9 intended to be rotated by a motor (not shown). The centrifuge 1 is fixed to the shaft 15 via the tulip, which is in the extension of the veil. When the mineral fiber forming device is in the fiberizing position, the axis 9 is vertical. The axis 9 is the axis of symmetry of the centrifuge.

The shaft 15 is hollow. At its upper end, the shaft 15 is connected to means for supplying molten glass. At its lower end, the shaft 15 is connected to the centrifuge when the latter is provided with a bottom, as can be seen in FIG. Alternatively, if the centrifuge 1 is devoid of background, the shaft 15 is connected to a basket. In the case of a device with basket, the basket is located inside the centrifuge 1, itself attached to the shaft 15. The basket, also fixed on the shaft 15, is intended to be rotated with the centrifuge 1 and the shaft 15. The basket comprises an annular wall pierced with a plurality of orifices.

When the mineral fiber forming device is in operation, the centrifuge 1 and the shaft 15, as well as, if appropriate, the basket, are rotated about the axis 9 of the shaft 15. From the molten glass 6 flows in the shaft 15, from the molten glass supply means, to the bottom of the plate or into the basket, in which the molten glass is spread 6. In the case of a centrifuge with bottom, a permanent reserve of molten glass 6 is formed against the annular wall 10 under the effect of rotation. In the case of a bottomless centrifuge with basket, the molten glass is projected, under the effect of rotation, on the annular wall of the basket, passes through the plurality of orifices of the basket and, in the form of bulky filaments, is projected onto the peripheral wall 10 of the centrifuge 1. A permanent pool of molten glass 6 is then formed in the bottomless centrifuge against the annular wall under the effect of rotation. The permanent pool of molten glass 6 supplies the plurality of orifices 1 1 pierced in the annular wall 10 of the centrifuge 1 to form flow cones extending forward of the fibers.

The orifices 1 1 of the annular wall 10 of the centrifuge 1 are preferably more numerous and of smaller diameter than the orifices of an annular wall of a centrifuge used with an internal combustion burner because the drawing is less efficient with heating by induction with burner heating by internal combustion. Thus, the annular wall 10 of the centrifuge 1 preferably comprises between 5000 and 25000 orifices and the orifices 1 1 preferably have a diameter of between 0.2 mm and 0.5 mm for a dish diameter of 200 mm.

The mineral fiber forming device also comprises a first annular inductor 2 adapted to heat the upper part of the annular wall 10 of the centrifuge 1. The first annular inductor 2 may also be adapted to further heat the web 13 of the centrifuge 1. The first annular inductor 2 is for example disposed above the centrifuge 1, close to the web 13 and the annular wall 10. The first annular inductor 2 is for example constituted by coils comprising between one and four copper turns, for example between two and four copper turns. The annular inductor 2 is preferably provided with field concentrators, for example ferrite, which make it possible to direct the magnetic field towards the plate in order to heat only the plate and, thus, to protect the other metal parts of the device . The annular inductor 2 is used to heat the annular wall at a temperature between 1000 and 1200 ° C.

The mineral fiber forming device also comprises a second annular inductor 5 adapted to heat the lower part of the annular wall 10 of the centrifuge 1. The second annular inductor may also be adapted to further heat the area of the centrifuge located below the annular wall 10. The second annular inductor 5 is for example located under the centrifuge. The second annular inductor 5 consists for example of coils comprising between one and four copper turns, for example between two and four copper turns. The annular inductor 5 is preferably provided with field concentrators, for example ferrite, which make it possible to direct the magnetic field towards the plate in order to heat only the plate and, thus, to protect the other metal parts of the device . The set of two annular inductors 2 and 5 has for example a power of 20 to 150 kW, for example 20 to 70 kW.

The operating frequency of the first and second annular inductors 2, 5 is for example between 1 and 300 kH. The second annular inductor 5 is for example connected with the first annular inductor 2, in series or in parallel, so that the magnetic fields of the first and second annular inductors 2, 5 are in phase to avoid the effects of mutual or the out of phase fields that would cancel each other out.

Alternatively, the first and second annular inductors 2, 5 are powered by two independent circuits, preferably independently powered to control and regulate their power independently. The generators of which in such a way that the effects of mutuality must be avoided or, at least, limited.

The heating of the annular band by two different zones (upper and lower) makes it possible to have a temperature gradient on the height of the centrifuge 1. This makes it possible to control the viscosity of the glass on the height of the annular band and, thus, to manufacture mineral fibers having more homogeneous dimensions and properties. When the first and second annular inductors 2, 5 are in series or in parallel, the difference in heating temperature between the upper zone and the lower zone of the annular band is adjusted by adjusting the position, the number and the diameter, for example turns of each annular inductor. When the first and second annular inductors 2, 5 are independently powered, the temperature setting on the two areas of the annular band is facilitated because the power can be adjusted independently for each annular inductor.

The upper portion of the annular band heated by the first annular inductor 2 and the lower portion of the annular band heated by the second annular inductor 5 may have a partial overlap area. The recovery zone can not be total, otherwise the possibility of having a temperature gradient would disappear.

The mineral fiber forming device also comprises a blowing ring 4 disposed above the centrifuge 1, and adapted to blow air on the fibers emerging from the centrifuge, preferably vertically and downwards, so as to fold down to a receiving mat under the fiberizing device. The blower ring 4 can blow air at an angle of at most 25 ° to the vertical, in the direction of the annular wall 10. pressure of the blowing stream at the outlet of the blower ring 4 is preferably between 1 and 2 bar.

The mineral fiber forming device may also comprise a second blast ring 3 disposed above the centrifuge 1, close to the web 13. The second blast ring 3 is adapted to blow air towards the web 13 , preferably vertically and downward. The pressure of the blast stream at the outlet of the blast ring 3 is preferably between 0.5 and 2 bar.

When the second blast ring 3 is present, the jets of air blown by the two blowing rings 3, 4 meet and create, at their intersection, a turbulence zone. This turbulence zone is located close to the annular wall 10. The turbulence produced makes it possible to stretch the mineral fibers even more than with centrifugal force alone.

As a variant, the blowing ring 4 may comprise several concentric air outlets but more or less distant from the axis 9. Or, the mineral fiber forming device may comprise several first blowing rings 4 arranged one above the other. above others, with a diameter slightly different from each other. These variants allow to have several concentric air jets which create a turbulence zone favorable to improved fiber stretching.

These different variants can be combined with each other. Optionally, the mineral fiber-forming device may also include an internal burner (not shown). The internal burner is used to heat the centrifuge 1 at the start of the mineral fiber formation process so that the molten glass arrives in a centrifuge 1 which is not cold to prevent crystallization of the glass. The internal burner is preferably used at startup so as to avoid a large production of carbon dioxide. The gas flow rate of the internal burner is less than 5, for example less than 3 Nm ³ / h.

Preferably, the centrifuge 1 is heated only by the two annular inductors 2, 5 without using an internal burner. Thus, the carbon dioxide content emitted by the mineral fiber-forming device can be zero. In addition, the mineral fiber forming device has a yield that can reach 75% or more, instead of only 30% with an internal combustion burner, and that for comparable operating temperatures. The mineral fiber forming device according to the invention thus allows an energy gain.

The mineral fiber forming device also preferably comprises a mineral fiber sizing ring (not shown) located under the centrifuge.

According to a variant not shown, the device for forming mineral fibers comprises a centrifuge open on the top, without veil or tulip, with only an annular wall closed down by a bottom. The bottom is attached to the lower end of a solid tree. The centrifuge is rotated about its axis of symmetry by the rotation of the hollow shaft about the axis of symmetry of the hollow shaft. The molten glass is fed into the plate by a pipe that is carried away from the axis of symmetry of the centrifuge. The molten glass supply pipe does not rotate with the hollow shaft and the centrifuge. The annular inductor 2 is disposed above the annular wall 10, so as to heat at least the upper part of the annular wall 10. The device comprises a single blower ring 4, disposed above the centrifuge 1, way to blow air on the fibers exiting the centrifuge, preferably vertically, so as to fold to a receiving mat located under the fiberizing device. The remainder is identical to the embodiment described according to FIG.

The invention also relates to a process for forming inorganic fibers by internal centrifugation. This method implements the device according to the invention, where the fiber material is poured into the centrifuge 1. The use of the centrifuge according to the invention thus makes it possible to improve the energy efficiency of the process and to reduce or even cancel the production of carbon dioxide.

The mineral fibers obtained by the mineral fiber forming device according to the invention are used to produce thermal and / or acoustic insulation products.

Claims

1. A mineral fiber forming device comprising:

- a centrifuge (1) adapted to rotate about an axis of rotation (9), the centrifuge (1) comprising an annular wall (10) pierced with a plurality of orifices (1 1), the annular wall (10) having as an axis of symmetry the axis of rotation (9),

a first annular inductor (2) adapted to heat the upper part of the annular wall (10),

- A second annular inductor (5), adapted to heat the lower portion of the annular wall (10).

2. Device according to claim 1, further comprising a first blower ring (4) adapted to blow air on the mineral fibers intended to exit the plurality of orifices (1 1) of the annular wall (10). in order to drive them to a conveyor belt for receiving and conveying the fibers.

3. Device according to claim 2, further comprising a second blower ring (3) adapted to blow air on a zone of the centrifuge located above the annular wall (10), the cooperation of the first and second rings blowing zone (3, 4) creating a zone of turbulence near the annular wall (10) of the centrifuge (1), this turbulence zone allowing additional stretching of the mineral fibers intended to exit the plurality of orifices (1 1 ) of the annular wall (10).

4. Device according to claim 2, further comprising at least two first concentric blow rings (4) of different diameters, the cooperation of the first blow crowns creating a zone of turbulence in the vicinity of the annular wall (10). centrifuge (1), this turbulence zone allowing additional stretching of the mineral fibers intended to exit the plurality of orifices (1 1) of the annular wall (10).

5. Device according to one of claims 2 to 4, wherein the first annular ring (4) comprises a plurality of concentric air outlets creating an area of turbulence near the annular wall (10) of the centrifuge. geur (1), this turbulence zone allowing additional stretching of the mineral fibers intended to exit the plurality of orifices (1 1) of the annular wall (10).

6. Device according to one of claims 1 to 5, wherein the first and second annular inductors (2, 5) are connected in series or in parallel or are supplied independently of one another.

7. Device according to one of claims 1 to 6, further comprising an internal burner adapted to be used at startup of the mineral fiber forming device.

8. Device according to one of claims 1 to 7, wherein the centrifuge (1) comprises a bottom.

9. Device according to one of claims 1 to 7, wherein the centrifuge (1) comprises no bottom and comprises a basket.

10. Device according to one of claims 1 to 9, further comprising a sizing ring mineral fibers located under the centrifuge (1).

1 1. Process for the formation of inorganic fibers by internal centrifugation, implementing the device according to one of claims 1 to 10, in which the material to be fibered is poured into the centrifuge (1).